The invention relates to improved interconnections between multi-layer conductive devices using bridge layers.
An important and continuing goal in the computer and electronics industries is that of increasing signal or conductive path density and bandwidth of conductive devices, such as printed circuit boards (PCB""s). This has lead to the development of multi-layer PCB""s having more than one layer of densely packed, high speed conductive paths or traces.
Electronic assemblies having more than one such PCB need to have a means of interconnecting the PCB""s to each other to form a conductive network. Connectors used to connect together PCB""s, however, tend to restrict the bandwidth of the network. For example, pin and socket type connectors create impedance discontinuities in traces, which reduces bandwidth. Furthermore, such connectors provide limited contact density, thereby restricting the number of useable connections achievable between the PCB""s.
The invention addresses the shortcomings of the prior art by providing a conductive network including at least one bridge layer for joining together conductive devices. With such an arrangement, bandwidth and trace density of the conductive devices can be maximized.
Under the invention, a conductive network includes a first conductive device having multiple first signal layers. Each first signal layer has a first substrate and a plurality of first conductive traces disposed on one side of the first substrate. The network further includes a second conductive device having multiple second signal layers. Each second signal layer has a second substrate and a plurality of second conductive traces disposed on one side of the second substrate. In addition, the network includes at least one bridge layer for electrically joining together the first and second conductive devices. The at least one bridge layer has a bridge substrate and a plurality of bridge traces supported by the bridge substrate.
Each first signal layer also preferably has a first ground plane disposed on a side of the first substrate opposite from the first conductive traces, and each second signal layer preferably has a second ground plane disposed on a side of the second substrate opposite from the second conductive traces.
In one embodiment of the invention, the conductive network includes a first conductive device having multiple first signal layers. Each first signal layer has a first substrate, a plurality of first conductive traces disposed on one side of the first substrate, and a first ground plane disposed on an opposite side of the first substrate. A first spacer assembly is connected to the first conductive device and includes a first housing that receives the first signal layers. The first spacer assembly further includes a plurality of first spacers, and each first spacer is disposed between adjacent first signal layers for spacing the adjacent first signal layers apart. The network further includes a second conductive device having multiple second signal layers. Each second signal layer has a second substrate, a plurality of second conductive traces disposed on one side of the second substrate, and a second ground plane disposed on an opposite side of the second substrate. A second spacer assembly is connected to the second conductive device and includes a second housing that receives the second signal layers. The second spacer assembly further includes a plurality of second spacers. Each second spacer is disposed between adjacent second signal layers for spacing the adjacent second signal layers apart. A bridging assembly is engageable with the first and second spacer assemblies. The bridging assembly includes a third housing, a plurality of bridge layers disposed in the third housing, and a plurality of separators that cooperate with the bridge layers to separate select bridge layers from each other so as to receive select first and second signal layers therebetween. The bridge layers are configured to electrically join together the first and second signal layers when the bridging assembly is engaged with the spacer assemblies.
In another embodiment of the invention, the conductive network includes a first conductive device having alternating first bridge layers and first signal layers that cooperate to define a first staggered step configuration. Each first signal layer has a first substrate, a plurality of first conductive traces disposed on one side of the first substrate, and a first ground plane disposed on an opposite side of the first substrate. The network further includes a second conductive device having alternating second bridge layers and second signal layers that cooperate to define a second staggered step configuration. Each second signal layer has a second substrate, a plurality of second conductive traces disposed on one side of the second substrate, and a second ground plane disposed on an opposite side of the second substrate. The first and second staggered step configurations are alignable with each other such that each first bridge layer electrically joins first and second conductive traces, and each second bridge layer electrically joins first and second ground planes.
These and other objects, features and advantages of the invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in conjunction with the accompanying drawings.